1. Field of the Invention
The present invention relates to a work allotment system for automatically determining respective quantities of various work to be allotted to a number of diverse available EDS (electrical distribution system, hereafter sometimes called "wiring harness") fabrication machines in consideration of specified particulars for individual circuits to be prefabricated by or in the machines for fabrication of required EDS products, as well as conditions and performances of the machines.
2. Description of Relevant Art
Automobiles employ various types of EDS, which typically comprise assemblies of electric wires amounting to several hundreds to about one thousand in wire number, ranging about several tens of centimeters in wire length. Such wires have their desirable lengths and desirable termination figures set through a prefabrication process including three steps: a cutting step in which an electric wire wound on a roll is unrolled straight and cut in a desirable wire length; a stripping step in which the cut wire is stripped along a desirable strip length of an insulation cover at either or both of its ends; and a crimping or solder-less connection step in which a desirable terminal is attached to the stripped wire end. After such a prefabrication, respective wires have their connectors fixed thereto as well as their housings fitted thereon, and are arranged in their desirable layout patterns different by automobiles and assembled, as necessary, to provide complete EDS products. Each wire constitutes a single circuit in any EDS that may include 1000 or more circuits. Some circuits may have accessories such as a conduit or tube fitted thereon, when prefabricated.
In usual, the fabrication of an EDS comprises a "lot production" including the prefabrication process in which a variety of electric wires are cut in lengths and cut wires are stripped at their ends and terminated by solder-less terminals, and a "set production" in which prefabricated circuits are assembled. The lot production is automated by a number of available EDS fabrication machines different in function and/or performance, covering varieties of work fields in the prefabrication process.
In a conventional system, an eventual number of various EDS order reception sheets at a factory were analyzed by technical staffs to know respective numbers of necessary circuits to be prefabricated, and associated data were collected and listed to be printed in the form of circuit-level order reception tables, which were analyzed by an expert of EDS work allotment, who determined respective daily quantities of circuit prefabrication work to be allotted to a limited number of available EDS fabrication machines, by reference to printed books describing technical characteristics of the machines, such as applicable wire types, terminal types and circuit accessories. Then, for each EDS fabrication machine, an allotted quantity of work was specified in a printed EDS fabrication instruction book prepared for a daily service of the machine.
A very simplified situation is now supposed, for example, such that a total of three different machines are available for a lot production of a total of three types of circuits that are necessary for a set production of required quantities of two or more wiring harness assemblies for promised ex-factory dates, which may be today and tomorrow. A first machine is adaptive for the prefabrication of each of an A-type and a B-type circuit, a second machine, simply for the B-type circuit, and a third machine, for any of the A-type, the B-type and a C-type circuit. The three machines have their production rates individually variable by the circuit types. Further, for the three types of circuits, required quantities are different. Still more, the set production of any wiring harness assembly cannot start until necessary lot quantities of the three types of circuits have become available therefor.
For such an EDS fabrication work allotment service, even a skilled person took much time. Still less, any person on the way of a long training might have, not merely a wasted time, but also an inefficient allotment, incurring a reduced EDS productivity.